Monolithic refractories are well established as linings for a range of holding and melting applications during the processing of Aluminium. The refractory lining in an Aluminium furnace has to withstand a wide variety of physical and chemical environments. Each of the different furnace zones presents a different set of operating conditions, in terms of peak temperature, temperature fluctuation, metal contact, salt contact, impact from ingot loading, etc. Therefore, in order for a monolithic material to successfully perform in a particular area of the furnace, it needs to be able to cope with the specific environmental conditions in that region of the furnace.
Aluminium producers continue to strive to increase productivity through their Melt-Hold furnaces to maintain competitiveness. The use of more poweful burners to increase heat input to the furnace is therefore becoming increasingly common practice. But faster melting leads to increased metal losses from surface oxidation and to segregation from large heat gradients. These effects are countered by increased use of fluxes and increased stirring. Given the increasingly challenging environment within which the refractory lining has to work, traditional lining solutions can no longer be relied upon to provide the service lives that were previously achieved. Therefore, a new generation of furnace lining materials is required to cope with today's aluminium furnace.
A study of working practices and furnace operating conditions at a number of Al producers highlighted those areas of Al melt-hold furnaces that limit campaign life in both the metal contact and non-metal contact regions. These are the regions which require the most frequent repairs, leading to expensive downtime. This paper describes a package of newly developed monolithic materials, designed specifically to enhance performance in these life limiting furnace zones to provide the Al producer with improved production efficiency through extended campaign times
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